#!/bin/bash
#
# Developed by Fred Weinhaus 7/17/2018 .......... 7/18/2018
#
# ------------------------------------------------------------------------------
# 
# Licensing:
# 
# Copyright © Fred Weinhaus
# 
# My scripts are available free of charge for non-commercial use, ONLY.
# 
# For use of my scripts in commercial (for-profit) environments or 
# non-free applications, please contact me (Fred Weinhaus) for 
# licensing arrangements. My email address is fmw at alink dot net.
# 
# If you: 1) redistribute, 2) incorporate any of these scripts into other 
# free applications or 3) reprogram them in another scripting language, 
# then you must contact me for permission, especially if the result might 
# be used in a commercial or for-profit environment.
# 
# My scripts are also subject, in a subordinate manner, to the ImageMagick 
# license, which can be found at: http://www.imagemagick.org/script/license.php
# 
# ------------------------------------------------------------------------------
# 
####
#
# USAGE: shimmer [-f frames] [-d delay] [-r rate] [-a amount] [-F fcolor] infile outfile
# USAGE: shimmer [-h or -help]
#
# OPTIONS:
#
# -f     frames     number of frames to generate in the animation; integer>0; default=15
# -d     delay      animation delay between frames; integer>0; default=5 
# -r     rate       rate of change in chirp wavelength; integer>0; default=3
# -a     amount     displacement amount; integer>0; default=10
# -F     fcolor     fade color for the reflection; any valid opaque IM color is 
#                   allowed; default=no fade; typical color is white.
#
###
#
# NAME: SHIMMER 
# 
# PURPOSE: Creates a reflected heat shimmering effect animation.
# 
# DESCRIPTION: SHIMMER creates a reflected heat shimmering effect animation. 
# 
# 
# OPTIONS: 
# 
# -f frames ... FRAMES are the number of frames to generate in the animation. Value 
# are integers>0. The default=15.
# 
# -d delay ... DELAY is animation delay between frames in ticks. Values are integers>0. 
# The default=5.
# 
# -r rate ... RATE of change in the chirp distortion to be applied. Values are 
# integers>0. A chirp is a sinusoidal wave whose wavelength/frequency changes as a 
# function of distance along the wave. The rate value is the exponent used in the 
# chirp equation. Larger values ramp the chirp faster. The default=3.
# 
# -a amount ... AMOUNT of displacement. Values are integers>=0. The default=10.
# 
# -F fcolor ... FCOLOR is the fade color for the reflection. Any valid opaque IM color 
# is allowed. Te default=no fade. Typical color is white.
# 
# REFERENCE: 
# https://en.wikipedia.org/wiki/Chirp
# 
# CAVEAT: No guarantee that this script will work on all platforms, 
# nor that trapping of inconsistent parameters is complete and 
# foolproof. Use At Your Own Risk. 
# 
######
#

# set default values
frames=15
delay=5
rate=3
amount=10
fcolor=""

# set directory for temporary files
dir="."    # suggestions are dir="." or dir="/tmp"

# set up functions to report Usage and Usage with Description
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
usage1() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^###/g;  /^#/!q;  s/^#//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}
usage2() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^######/g;  /^#/!q;  s/^#*//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}


# function to report error messages
errMsg()
	{
	echo ""
	echo $1
	echo ""
	usage1
	exit 1
	}


# function to test for minus at start of value of second part of option 1 or 2
checkMinus()
	{
	test=`echo "$1" | grep -c '^-.*$'`   # returns 1 if match; 0 otherwise
    [ $test -eq 1 ] && errMsg "$errorMsg"
	}

# test for correct number of arguments and get values
if [ $# -eq 0 ]
	then
	# help information
   echo ""
   usage2
   exit 0
elif [ $# -gt 12 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
			# get parameter values
			case "$1" in
		  -help|-h)    # help information
					   echo ""
					   usage2
					   exit 0
					   ;;
				-f)    # get frames
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID FRAMES SPECIFICATION ---"
					   checkMinus "$1"
					   frames=`expr "$1" : '\([0-9]*\)'`
					   [ "$frames" = "" ] && errMsg "--- FRAMES=$frames MUST BE A NON-NEGATIVE INTEGER (with no sign) ---"
					   test1=`echo "$frames == 0" | bc`
					   [ $test1 -eq 1 ] && errMsg "--- FRAMES=$frames MUST BE A POSITIVE INTEGER ---"
					   ;;
				-d)    # get delay
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID DELAY SPECIFICATION ---"
					   checkMinus "$1"
					   delay=`expr "$1" : '\([0-9]*\)'`
					   [ "$delay" = "" ] && errMsg "--- DELAY=$delay MUST BE A NON-NEGATIVE INTEGER (with no sign) ---"
					   test1=`echo "$delay == 0" | bc`
					   [ $test1 -eq 1 ] && errMsg "--- DELAY=$delay MUST BE A POSITIVE INTEGER ---"
					   ;;
				-r)    # get rate
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID RATE SPECIFICATION ---"
					   checkMinus "$1"
					   rate=`expr "$1" : '\([0-9]*\)'`
					   [ "$rate" = "" ] && errMsg "--- RATE=$rate MUST BE A NON-NEGATIVE INTEGER (with no sign) ---"
					   test1=`echo "$rate == 0" | bc`
					   [ $test1 -eq 1 ] && errMsg "--- RATE=$rate MUST BE A POSITIVE INTEGER ---"
					   ;;
				-a)    # get amount
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID AMOUNT SPECIFICATION ---"
					   checkMinus "$1"
					   amount=`expr "$1" : '\([0-9]*\)'`
					   [ "$amount" = "" ] && errMsg "--- AMOUNT=$amount MUST BE A NON-NEGATIVE INTEGER (with no sign) ---"
					   test1=`echo "$amount == 0" | bc`
					   [ $test1 -eq 1 ] && errMsg "--- AMOUNT=$amount MUST BE A POSITIVE INTEGER ---"
					   ;;
				-F)    # get fcolor
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID AMOUNT SPECIFICATION ---"
					   checkMinus "$1"
					   fcolor="$1"
					   ;;
			 	-)    # STDIN and end of arguments
					   break
					   ;;
				-*)    # any other - argument
					   errMsg "--- UNKNOWN OPTION ---"
					   ;;
		     	 *)    # end of arguments
					   break
					   ;;
			esac
			shift   # next option
	done
	#
	# get infile and outfile
	infile="$1"
	outfile="$2"
fi

# test that infile provided
[ "$infile" = "" ] && errMsg "NO INPUT FILE SPECIFIED"

# test that outfile provided
[ "$outfile" = "" ] && errMsg "NO OUTPUT FILE SPECIFIED"


# set up temporaries
tmp1A="$dir/shimmer_1_$$.mpc"
tmp1B="$dir/shimmer_1_$$.cache"
tmp2A="$dir/shimmer_2_$$.mpc"
tmp2B="$dir/shimmer_2_$$.cache"
trap "rm -f $tmp1A $tmp1B $tmp2A $tmp2B;" 0
trap "rm -f $tmp1A $tmp1B $tmp2A $tmp2B; exit 1" 1 2 3 15
#trap "rm -f $tmp1A $tmp1B; exit 1" ERR



# test input image
convert -quiet "$infile" +repage "$tmp1A" ||
	errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"

# get image dimensions
WxH=`convert -ping $tmp1A -format "%wx%h" info:`
ww=`echo $WxH | cut -dx -f1`
hh=`echo $WxH | cut -dx -f2`

if [ "$fcolor" = "" ]; then
	# use subshell processing to avoid saving separate frames
	(
	for ((k=0; k<frames; k++)); do
	convert $tmp1A -write mpr:img \
	\( -size 1x${hh} xc: -fx "0.5*sin($k*2*pi/$frames+2*pi*(j/(0.5*h))^$rate)+0.5" -scale ${ww}x${hh}! \) \
	-define compose:args=0,$amount -compose displace -composite -flip \
	mpr:img +swap -append miff:-
	done
	) | convert -delay $delay - -loop 0 "$outfile"
else
	# use subshell processing to avoid saving separate frames
	convert -size ${ww}x${hh} gradient: -flip $tmp2A
	(
	for ((k=0; k<frames; k++)); do
	convert $tmp1A -write mpr:img \
	\( -size 1x${hh} xc: -fx "0.5*sin($k*2*pi/$frames+2*pi*(j/(0.5*h))^$rate)+0.5" -scale ${ww}x${hh}! \) \
	-define compose:args=0,$amount -compose displace -composite -compose over \
	$tmp2A -alpha off -compose copy_opacity -composite -compose over -background "$fcolor" -flatten -flip \
	mpr:img +swap -append miff:-
	done
	) | convert -delay $delay - -loop 0 "$outfile"
fi

exit 0




